http://www.caa.co.uk/docs/1428/Summa...009May2010.pdf
Covers it.
Passenger
A passenger is defined in the Order as a person other than a member of the crew. Crew means members of the flight crew, cabin attendants and persons authorised to supervise training and carry out tests. It will be appreciated that observers, cameramen and other persons carried to operate particular pieces of equipment on board an aircraft will, if they do not fall within the definition of crew, be passengers. In so far as payment has been made to enable them to be carried it will be a public transport flight.
As a cessna is a single crew aircraft...
The single ops guys are ariel work but as soon as there is a photographer onboard who is being payed its public transport. The photographer is not counted as crew. Freelance photographers who hire aircraft and pilot and gain benefit from the photos also fall foul of public transport.
Companys hiring aircraft plus pilot plus photographer are in the same boat as the police operating with an observer or a helimed flight/airambulance.
An just to add another quote
This public transport definition has been interpreted literally as having a very wide scope. This is intentional. It includes the typical commercial passenger carrying flight, where a customer buys a ticket to fly from A to B on holiday or business. But it also captures a variety of other operations. For example, if an operator is paid to carry a police observer, that observer will be a passenger and it will be a public transport flight. Similarly where a power company pays for its observer to be carried to inspect power lines or where a television company pays for its camera crew to be carried it will be a public transport flight. Where an observer or camera operator is employed by the operator, it is quite likely that the customer will not be paying directly for their carriage so that it will not be public transport.
So it all depends on the set up. If the camera man is employed by the operator your fine. If anything else its public transport requiring an AOC.